hemodynamic interactions

Question 1

what are venous compartments separated into?

Answer 1

Peripheral and central

Question 2

What is crucial for determining how well a cv system is operating?

Answer 2

Cardiac filling pressure

Question 3

What is very sensitive to small changes in pressure?

Answer 3

EDV

Question 4

How much does it take to fill the circulatory system. No pressure or stretching?

Answer 4

3.5liters

Question 5

What are the 2 things that affect the mean circulatory filling pressure?

Answer 5

1. circulating blood volume

2. state of peripheral venous tone

Question 6

What is the amount of contents in the peripheral venous compartment?

Answer 6

2.5 liters

which with increase tone is added to the circulatory system!

Question 7

Would arteries of capillaries affect other compartments with the necessary pressure?

Answer 7

No, their volume is small and would have a negligible effect on mean circulatory filling pressure

Question 8

Does the presence of flow to the circuit change the total volume or mean circulatory filling pressure?

Answer 8

NO

• flow induced distribution
• PVS usually close to mean circulatory filling pressure

Question 9

Which is more compliant veins or arteries?

Answer 9

Veins. Added blood doesnt affect pressure much

** Veins 50x more compliant

Arteries, pressures affected greatly by adding blood to arterial system

Question 10

With flow does pressure in the peripheral venous system change much?

Answer 10

Nope

Flow or now flow doesnt affect mean filling pressure

Question 11

What is a good indicator of the circulatory status?

Answer 11

Central venous pressure

• CV system adjusts operation continually to meet changing metabolic demands

Question 12

Is the CV system closed or open? What are the consequences of this?

Answer 12

Closed

• change in pressure in one area affects pressure, flow and volume throughout the circuit

Question 13

What consists of the central venous compartment?

Answer 13

Great veins of thorax and right atrium

Question 14

What is venous return?

Answer 14

Rate at which blood is coming back to the central venous compartment

• should match cardiac output

Question 15

What happens when CO doesnt match venous return?

Answer 15

Volume of central venous compartment must be changing

Produces change in central venous pressure

Question 16

What is the role of CVP?

Answer 16

always driven to a value that makes Cardiac output = venous return

Question 17

what essentially is the same thing as peripheral venous pressure?

Answer 17

Mean circulatory filling pressure

PV and CV compartment must equal the same
Q=^P/R

Question 18

What are the 2 influences of peripheral venous pressure?

Answer 18

1. Changes in blood volume (increase in volume in a fixed compartment increases pressure)
2. Changes in venous tone (vasoconstriction via sympathetics)

Question 19

When central venous pressure decreases what happens to venous return?

Answer 19

increases

inverse relationship

Question 20

If pressure diff between CV and PV compartment determining venous return then??

Answer 20

Increase peripheral venous pressure works just as well as dropping central venous pressure on increasing venous return.

Question 21

When are CO and VR equal to one another?

Answer 21

at central venous pressure of 2 mmHg

both affected by central venous pressure

Question 22

What determines where the cardiac and venous function curves intersect?

Answer 22

Heart and peripheral vasculature

Question 23

DO cardiac sympathetics affect the venous function curve?

Answer 23

NO

Question 24

What is the hallmark of of CHF?

Answer 24

Very high central venous pressure

Question 25

What does high central venous pressure do to a CVP CO/VR curve?

Answer 25

Right shift

Question 26

What results in a left shift of the CVP CO/VR curve?

Answer 26

Low central venous pressure

Question 27

What is mean circulatory filling pressure?

Answer 27

Hypothetical pressure related to filling of the the whole systems vasculature without stretching any of its walls or developing any internal pressure.

• Filling of the anatomical space

Question 28

How much volume of blood do we have? How much more is this than the volume to fill the entire anatomical circuit? What would the pressure be with increased volume? (equation used)?

Answer 28

a. 4.5l
b. 1000
c. C=^V/^P thus P=^V/C–> P=1000/140=

• 7mmHg–> mean circ filling pressure or pressure that would result in the absence of flow!